binaries/assimp-3.1.1/code/Subdivision.cpp

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

Copyright (c) 2006-2012, assimp team
All rights reserved.

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with or without modification, are permitted provided that the 
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* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
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  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.

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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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*/

#include "AssimpPCH.h"

#include "Subdivision.h"
#include "SceneCombiner.h"
#include "SpatialSort.h"
#include "ProcessHelper.h"
#include "Vertex.h"

using namespace Assimp;
void mydummy() {}

// ------------------------------------------------------------------------------------------------
/** Subdivider stub class to implement the Catmull-Clarke subdivision algorithm. The 
 *  implementation is basing on recursive refinement. Directly evaluating the result is also
 *  possible and much quicker, but it depends on lengthy matrix lookup tables. */
// ------------------------------------------------------------------------------------------------
class CatmullClarkSubdivider : public Subdivider
{

public:

	void Subdivide (aiMesh* mesh, aiMesh*& out, unsigned int num, bool discard_input);
	void Subdivide (aiMesh** smesh, size_t nmesh,
		aiMesh** out, unsigned int num, bool discard_input);

	// ---------------------------------------------------------------------------
	/** Intermediate description of an edge between two corners of a polygon*/
	// ---------------------------------------------------------------------------
	struct Edge
	{
		Edge()
			: ref(0)
		{}
		Vertex edge_point, midpoint;
		unsigned int ref;
	};



	typedef std::vector<unsigned int> UIntVector;
	typedef std::map<uint64_t,Edge> EdgeMap;

	// ---------------------------------------------------------------------------
	// Hashing function to derive an index into an #EdgeMap from two given
	// 'unsigned int' vertex coordinates (!!distinct coordinates - same 
	// vertex position == same index!!). 
	// NOTE - this leads to rare hash collisions if a) sizeof(unsigned int)>4
	// and (id[0]>2^32-1 or id[0]>2^32-1).
	// MAKE_EDGE_HASH() uses temporaries, so INIT_EDGE_HASH() needs to be put
	// at the head of every function which is about to use MAKE_EDGE_HASH().
	// Reason is that the hash is that hash construction needs to hold the
	// invariant id0<id1 to identify an edge - else two hashes would refer
	// to the same edge.
	// ---------------------------------------------------------------------------
#define MAKE_EDGE_HASH(id0,id1) (eh_tmp0__=id0,eh_tmp1__=id1,\
	(eh_tmp0__<eh_tmp1__?std::swap(eh_tmp0__,eh_tmp1__):mydummy()),(uint64_t)eh_tmp0__^((uint64_t)eh_tmp1__<<32u))


#define INIT_EDGE_HASH_TEMPORARIES()\
	unsigned int eh_tmp0__, eh_tmp1__;

private:

	void InternSubdivide (const aiMesh* const * smesh, 
		size_t nmesh,aiMesh** out, unsigned int num);
};


// ------------------------------------------------------------------------------------------------
// Construct a subdivider of a specific type
Subdivider* Subdivider::Create (Algorithm algo)
{
	switch (algo)
	{
	case CATMULL_CLARKE:
		return new CatmullClarkSubdivider();
	};

	ai_assert(false);
	return NULL; // shouldn't happen
}

// ------------------------------------------------------------------------------------------------
// Call the Catmull Clark subdivision algorithm for one mesh
void  CatmullClarkSubdivider::Subdivide (
	aiMesh* mesh, 
	aiMesh*& out,
	unsigned int num,
	bool discard_input
	)
{
	assert(mesh != out);
	Subdivide(&mesh,1,&out,num,discard_input);
}

// ------------------------------------------------------------------------------------------------
// Call the Catmull Clark subdivision algorithm for multiple meshes
void CatmullClarkSubdivider::Subdivide (
	aiMesh** smesh, 
	size_t nmesh,
	aiMesh** out, 
	unsigned int num,
	bool discard_input
	)
{
	ai_assert(NULL != smesh && NULL != out);

	// course, both regions may not overlap
	assert(smesh<out || smesh+nmesh>out+nmesh);
	if (!num) {
		
		// No subdivision at all. Need to copy all the meshes .. argh.
		if (discard_input) {
			for (size_t s = 0; s < nmesh; ++s) {
				out[s] = smesh[s];
				smesh[s] = NULL;
			}
		}
		else {
			for (size_t s = 0; s < nmesh; ++s) {
				SceneCombiner::Copy(out+s,smesh[s]);
			}
		}
		return;
	}

	std::vector<aiMesh*> inmeshes;
	std::vector<aiMesh*> outmeshes;
	std::vector<unsigned int> maptbl;

	inmeshes.reserve(nmesh);
	outmeshes.reserve(nmesh);
	maptbl.reserve(nmesh);

	// Remove pure line and point meshes from the working set to reduce the 
	// number of edge cases the subdivider is forced to deal with. Line and 
	// point meshes are simply passed through.
	for (size_t s = 0; s < nmesh; ++s) {
		aiMesh* i = smesh[s];
		// FIX - mPrimitiveTypes might not yet be initialized
		if (i->mPrimitiveTypes && (i->mPrimitiveTypes & (aiPrimitiveType_LINE|aiPrimitiveType_POINT))==i->mPrimitiveTypes) {
			DefaultLogger::get()->debug("Catmull-Clark Subdivider: Skipping pure line/point mesh");

			if (discard_input) {
				out[s] = i;
				smesh[s] = NULL;
			}
			else {
				SceneCombiner::Copy(out+s,i);
			}
			continue;
		}

		outmeshes.push_back(NULL);inmeshes.push_back(i);
		maptbl.push_back(s);
	}

	// Do the actual subdivision on the preallocated storage. InternSubdivide 
	// *always* assumes that enough storage is available, it does not bother
	// checking any ranges.
	ai_assert(inmeshes.size()==outmeshes.size()&&inmeshes.size()==maptbl.size());
	if (inmeshes.empty()) {
		DefaultLogger::get()->warn("Catmull-Clark Subdivider: Pure point/line scene, I can't do anything");
		return;
	}
	InternSubdivide(&inmeshes.front(),inmeshes.size(),&outmeshes.front(),num);
	for (unsigned int i = 0; i < maptbl.size(); ++i) {
		ai_assert(outmeshes[i]);
		out[maptbl[i]] = outmeshes[i];
	}

	if (discard_input) {
		for (size_t s = 0; s < nmesh; ++s) {
			delete smesh[s];
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Note - this is an implementation of the standard (recursive) Cm-Cl algorithm without further 
// optimizations (except we're using some nice LUTs). A description of the algorithm can be found
// here: http://en.wikipedia.org/wiki/Catmull-Clark_subdivision_surface
//
// The code is mostly O(n), however parts are O(nlogn) which is therefore the algorithm's
// expected total runtime complexity. The implementation is able to work in-place on the same
// mesh arrays. Calling #InternSubdivide() directly is not encouraged. The code can operate
// in-place unless 'smesh' and 'out' are equal (no strange overlaps or reorderings). 
// Previous data is replaced/deleted then.
// ------------------------------------------------------------------------------------------------
void CatmullClarkSubdivider::InternSubdivide (
	const aiMesh* const * smesh, 
	size_t nmesh,
	aiMesh** out, 
	unsigned int num
	)
{
	ai_assert(NULL != smesh && NULL != out);
	INIT_EDGE_HASH_TEMPORARIES();

	// no subdivision requested or end of recursive refinement
	if (!num) {
		return;
	}

	UIntVector maptbl;
	SpatialSort spatial;

	// ---------------------------------------------------------------------
	// 0. Offset table to index all meshes continuously, generate a spatially
	// sorted representation of all vertices in all meshes.
	// ---------------------------------------------------------------------
	typedef std::pair<unsigned int,unsigned int> IntPair;
	std::vector<IntPair> moffsets(nmesh);
	unsigned int totfaces = 0, totvert = 0;
	for (size_t t = 0; t < nmesh; ++t) {
		const aiMesh* mesh = smesh[t];

		spatial.Append(mesh->mVertices,mesh->mNumVertices,sizeof(aiVector3D),false);
		moffsets[t] = IntPair(totfaces,totvert);

		totfaces += mesh->mNumFaces;
		totvert  += mesh->mNumVertices;
	}

	spatial.Finalize();
	const unsigned int num_unique = spatial.GenerateMappingTable(maptbl,ComputePositionEpsilon(smesh,nmesh));


#define FLATTEN_VERTEX_IDX(mesh_idx, vert_idx) (moffsets[mesh_idx].second+vert_idx)
#define   FLATTEN_FACE_IDX(mesh_idx, face_idx) (moffsets[mesh_idx].first+face_idx)

	// ---------------------------------------------------------------------
	// 1. Compute the centroid point for all faces
	// ---------------------------------------------------------------------
	std::vector<Vertex> centroids(totfaces);
	unsigned int nfacesout = 0;
	for (size_t t = 0, n = 0; t < nmesh; ++t) {
		const aiMesh* mesh = smesh[t];
		for (unsigned int i = 0; i < mesh->mNumFaces;++i,++n)
		{
			const aiFace& face = mesh->mFaces[i];
			Vertex& c = centroids[n];

			for (unsigned int a = 0; a < face.mNumIndices;++a) {
				c += Vertex(mesh,face.mIndices[a]);
			}

			c /= static_cast<float>(face.mNumIndices);
			nfacesout += face.mNumIndices;
		}
	}
	
	EdgeMap edges;

	// ---------------------------------------------------------------------
	// 2. Set each edge point to be the average of all neighbouring 
	// face points and original points. Every edge exists twice
	// if there is a neighboring face.
	// ---------------------------------------------------------------------
	for (size_t t = 0; t < nmesh; ++t) {
		const aiMesh* mesh = smesh[t];

		for (unsigned int i = 0; i < mesh->mNumFaces;++i)	{
			const aiFace& face = mesh->mFaces[i];

			for (unsigned int p =0; p< face.mNumIndices; ++p) {
				const unsigned int id[] = { 
					face.mIndices[p], 
					face.mIndices[p==face.mNumIndices-1?0:p+1]
				};
				const unsigned int mp[] = { 
					maptbl[FLATTEN_VERTEX_IDX(t,id[0])], 
					maptbl[FLATTEN_VERTEX_IDX(t,id[1])]
				};

				Edge& e = edges[MAKE_EDGE_HASH(mp[0],mp[1])];
				e.ref++;
				if (e.ref<=2) {
					if (e.ref==1) { // original points (end points) - add only once
						e.edge_point = e.midpoint = Vertex(mesh,id[0])+Vertex(mesh,id[1]);
						e.midpoint *= 0.5f;
					}
					e.edge_point += centroids[FLATTEN_FACE_IDX(t,i)];
				}
			}
		}
	}

	// ---------------------------------------------------------------------
	// 3. Normalize edge points
	// ---------------------------------------------------------------------
	{unsigned int bad_cnt = 0;
	for (EdgeMap::iterator it = edges.begin(); it != edges.end(); ++it) {
		if ((*it).second.ref < 2) {
			ai_assert((*it).second.ref);
			++bad_cnt;
		}
		(*it).second.edge_point *= 1.f/((*it).second.ref+2.f);
	}

	if (bad_cnt) {
		// Report the number of bad edges. bad edges are referenced by less than two
		// faces in the mesh. They occur at outer model boundaries in non-closed
		// shapes.
		char tmp[512];
		sprintf(tmp,"Catmull-Clark Subdivider: got %u bad edges touching only one face (totally %u edges). ",
			bad_cnt,static_cast<unsigned int>(edges.size()));

		DefaultLogger::get()->debug(tmp);
	}}

	// ---------------------------------------------------------------------
	// 4. Compute a vertex-face adjacency table. We can't reuse the code
	// from VertexTriangleAdjacency because we need the table for multiple
	// meshes and out vertex indices need to be mapped to distinct values 
	// first.
	// ---------------------------------------------------------------------
	UIntVector faceadjac(nfacesout), cntadjfac(maptbl.size(),0), ofsadjvec(maptbl.size()+1,0); {
	for (size_t t = 0; t < nmesh; ++t) {
		const aiMesh* const minp = smesh[t];
		for (unsigned int i = 0; i < minp->mNumFaces; ++i) {
			
			const aiFace& f = minp->mFaces[i];
			for (unsigned int n = 0; n < f.mNumIndices; ++n) {
				++cntadjfac[maptbl[FLATTEN_VERTEX_IDX(t,f.mIndices[n])]];
			}
		}
	}
	unsigned int cur = 0;
	for (size_t i = 0; i < cntadjfac.size(); ++i) {
		ofsadjvec[i+1] = cur;
		cur += cntadjfac[i];
	}
	for (size_t t = 0; t < nmesh; ++t) {
		const aiMesh* const minp = smesh[t];
		for (unsigned int i = 0; i < minp->mNumFaces; ++i) {
			
			const aiFace& f = minp->mFaces[i];
			for (unsigned int n = 0; n < f.mNumIndices; ++n) {
				faceadjac[ofsadjvec[1+maptbl[FLATTEN_VERTEX_IDX(t,f.mIndices[n])]]++] = FLATTEN_FACE_IDX(t,i);
			}
		}
	} 
	
	// check the other way round for consistency
#ifdef ASSIMP_BUILD_DEBUG

	for (size_t t = 0; t < ofsadjvec.size()-1; ++t) {
		for (unsigned int m = 0; m <  cntadjfac[t]; ++m) {
			const unsigned int fidx = faceadjac[ofsadjvec[t]+m];
			ai_assert(fidx < totfaces);
			for (size_t n = 1; n < nmesh; ++n) {
			
				if (moffsets[n].first > fidx) {
					const aiMesh* msh = smesh[--n];
					const aiFace& f = msh->mFaces[fidx-moffsets[n].first];
					
					bool haveit = false;
					for (unsigned int i = 0; i < f.mNumIndices; ++i) {
						if (maptbl[FLATTEN_VERTEX_IDX(n,f.mIndices[i])]==(unsigned int)t) {
							haveit = true; break;
						}
					}
					ai_assert(haveit);
					break;
				}
			}
		}
	}

#endif
	}

#define GET_ADJACENT_FACES_AND_CNT(vidx,fstartout,numout) \
	fstartout = &faceadjac[ofsadjvec[vidx]], numout = cntadjfac[vidx]

	typedef std::pair<bool,Vertex> TouchedOVertex;
	std::vector<TouchedOVertex > new_points(num_unique,TouchedOVertex(false,Vertex()));
	// ---------------------------------------------------------------------
	// 5. Spawn a quad from each face point to the corresponding edge points
	// the original points being the fourth quad points.
	// ---------------------------------------------------------------------
	for (size_t t = 0; t < nmesh; ++t) {
		const aiMesh* const minp = smesh[t];
		aiMesh* const mout = out[t] = new aiMesh();

		for (unsigned int a  = 0; a < minp->mNumFaces; ++a) {
			mout->mNumFaces += minp->mFaces[a].mNumIndices;
		}

		// We need random access to the old face buffer, so reuse is not possible.
		mout->mFaces = new aiFace[mout->mNumFaces];

		mout->mNumVertices = mout->mNumFaces*4;
		mout->mVertices = new aiVector3D[mout->mNumVertices];

		// quads only, keep material index
		mout->mPrimitiveTypes = aiPrimitiveType_POLYGON;
		mout->mMaterialIndex = minp->mMaterialIndex;

		if (minp->HasNormals()) {
			mout->mNormals = new aiVector3D[mout->mNumVertices];
		}

		if (minp->HasTangentsAndBitangents()) {
			mout->mTangents = new aiVector3D[mout->mNumVertices];
			mout->mBitangents = new aiVector3D[mout->mNumVertices];
		}

		for(unsigned int i = 0; minp->HasTextureCoords(i); ++i) {
			mout->mTextureCoords[i] = new aiVector3D[mout->mNumVertices];
			mout->mNumUVComponents[i] = minp->mNumUVComponents[i];
		}

		for(unsigned int i = 0; minp->HasVertexColors(i); ++i) {
			mout->mColors[i] = new aiColor4D[mout->mNumVertices];
		}

		mout->mNumVertices = mout->mNumFaces<<2u;
		for (unsigned int i = 0, v = 0, n = 0; i < minp->mNumFaces;++i)	{

			const aiFace& face = minp->mFaces[i];
			for (unsigned int a = 0; a < face.mNumIndices;++a)	{

				// Get a clean new face.
				aiFace& faceOut = mout->mFaces[n++];
				faceOut.mIndices = new unsigned int [faceOut.mNumIndices = 4];

				// Spawn a new quadrilateral (ccw winding) for this original point between:
				// a) face centroid
				centroids[FLATTEN_FACE_IDX(t,i)].SortBack(mout,faceOut.mIndices[0]=v++); 

				// b) adjacent edge on the left, seen from the centroid
				const Edge& e0 = edges[MAKE_EDGE_HASH(maptbl[FLATTEN_VERTEX_IDX(t,face.mIndices[a])],
					maptbl[FLATTEN_VERTEX_IDX(t,face.mIndices[a==face.mNumIndices-1?0:a+1])
					])];  // fixme: replace with mod face.mNumIndices? 

				// c) adjacent edge on the right, seen from the centroid
				const Edge& e1 = edges[MAKE_EDGE_HASH(maptbl[FLATTEN_VERTEX_IDX(t,face.mIndices[a])],
					maptbl[FLATTEN_VERTEX_IDX(t,face.mIndices[!a?face.mNumIndices-1:a-1])
					])];  // fixme: replace with mod face.mNumIndices? 

				e0.edge_point.SortBack(mout,faceOut.mIndices[3]=v++);
				e1.edge_point.SortBack(mout,faceOut.mIndices[1]=v++);

				// d= original point P with distinct index i
				// F := 0
				// R := 0
				// n := 0
				// for each face f containing i
				//    F := F+ centroid of f
				//    R := R+ midpoint of edge of f from i to i+1
				//    n := n+1
				//
				// (F+2R+(n-3)P)/n         
				const unsigned int org = maptbl[FLATTEN_VERTEX_IDX(t,face.mIndices[a])];
				TouchedOVertex& ov = new_points[org];

				if (!ov.first) {
					ov.first = true;

					const unsigned int* adj; unsigned int cnt;
					GET_ADJACENT_FACES_AND_CNT(org,adj,cnt);

					if (cnt < 3) {
						ov.second = Vertex(minp,face.mIndices[a]);
					}
					else {

						Vertex F,R;
						for (unsigned int o = 0; o < cnt; ++o) {
							ai_assert(adj[o] < totfaces);
							F += centroids[adj[o]];

							// adj[0] is a global face index - search the face in the mesh list
							const aiMesh* mp = NULL;
							size_t nidx;

							if (adj[o] < moffsets[0].first) {
								mp = smesh[nidx=0];
							}
							else {
								for (nidx = 1; nidx<= nmesh; ++nidx) {
									if (nidx == nmesh ||moffsets[nidx].first > adj[o]) {
										mp = smesh[--nidx];
										break;
									}
								}
							}

							ai_assert(adj[o]-moffsets[nidx].first < mp->mNumFaces);
							const aiFace& f = mp->mFaces[adj[o]-moffsets[nidx].first];
#				ifdef ASSIMP_BUILD_DEBUG
							bool haveit = false;
#				endif

							// find our original point in the face
							for (unsigned int m = 0; m < f.mNumIndices; ++m) {
								if (maptbl[FLATTEN_VERTEX_IDX(nidx,f.mIndices[m])] == org) {

									// add *both* edges. this way, we can be sure that we add
									// *all* adjacent edges to R. In a closed shape, every
									// edge is added twice - so we simply leave out the
									// factor 2.f in the amove formula and get the right
									// result.

									const Edge& c0 = edges[MAKE_EDGE_HASH(org,maptbl[FLATTEN_VERTEX_IDX(
										nidx,f.mIndices[!m?f.mNumIndices-1:m-1])])];
									// fixme: replace with mod face.mNumIndices? 

									const Edge& c1 = edges[MAKE_EDGE_HASH(org,maptbl[FLATTEN_VERTEX_IDX(
										nidx,f.mIndices[m==f.mNumIndices-1?0:m+1])])];
									// fixme: replace with mod face.mNumIndices? 
									R += c0.midpoint+c1.midpoint;

#						ifdef ASSIMP_BUILD_DEBUG
									haveit = true;
#						endif
									break;
								}
							}

							// this invariant *must* hold if the vertex-to-face adjacency table is valid
							ai_assert(haveit);
						}

						const float div = static_cast<float>(cnt), divsq = 1.f/(div*div);
						ov.second = Vertex(minp,face.mIndices[a])*((div-3.f) / div) + R*divsq + F*divsq;  
					}
				}
				ov.second.SortBack(mout,faceOut.mIndices[2]=v++);
			}
		}
	}

	// ---------------------------------------------------------------------
	// 7. Apply the next subdivision step. 
	// ---------------------------------------------------------------------
	if (num != 1) {
		std::vector<aiMesh*> tmp(nmesh);
		InternSubdivide (out,nmesh,&tmp.front(),num-1);
		for (size_t i = 0; i < nmesh; ++i) {
			delete out[i];
			out[i] = tmp[i];
		}
	}
}